Review of the contribution of radiolabelled tracers for tumour cell status imaging

Cancer develops as a result of an imbalance between cell proliferation and programmed cell death or apoptosis. Tumour cells are characterised by prolonged survival and uncontrolled proliferation. Tumour cells also acquire new functions, such as the capacity to migrate and colonise other organs by forming metastases. Cancer chemotherapy mainly acts by inducing apoptosis. However, resistance of human malignancies to multiple chemotherapeutic agents remains a major obstacle to the efficacy of treatment. Radiolabelled tracers used in Single Photon Emission Computed Tomography (SPECT) and more recently in Positron Emission Tomography (PET) screening in nuclear medicine have been developed to directly visualise in vivo biochemical and physiological parameters of tumour cells. These functional and molecular techniques have become an excellent research tool to study in vivo tumour biology. For instance, proliferation, apoptosis and multidrug resistance tracers have been complexed and studied on in vitro cellular models and several in vivo applications have been developed in the management of cancer patients. In this review, we focus on the radiotracers elaborated in the field of proliferation, apoptosis and MDR. We summarise the most recent studies in SPECT and PET imaging and their possible applications in oncology.